Transfer voltage controlling method and apparatus of image forming

Abstract

A transfer voltage controlling apparatus of an image forming apparatus includes a high voltage unit installed at one side of a sheet for generating a magnetic field around the sheet by applying a high voltage to the sheet, a conductor unit installed at the other side of the sheet for forming an induced current by the magnetic field transmitted through the sheet, an A/D converter for converting an analog signal of the current induced to the conductor unit into a digital signal, a microcontroller for receiving the output signal of the A/D converter, comparing the received signal with a reference signal to detect thickness of the sheet, and generating a control command of the transfer voltage corresponding to the thickness of the sheet, and a high voltage controller for receiving the control command from the microcontroller and applying the transfer voltage having a predetermined magnitude to a transfer unit. Since the transfer voltage applied to a transfer unit is varied/controlled according to the thickness of the sheet as well as the ambient temperature and humidity, the transfer efficiency can be enhanced and a better quality image can be obtained, accordingly.